Fluid (gas or liquid) streams can carry contaminant material therein. In many instances, it is desired to filter some or all of the contaminant material from the air stream. For example: air flow streams to engines, for example combustion air for motorized vehicles or for power generation equipment; gas (for example air) streams to gas turbine systems; gas (for example, air) streams to various combustion furnaces; and, cabin air and air in industrial systems, carry particulate contaminant therein that should be filtered. It is preferred for such systems, that selected contaminant material be removed from (or have its level reduced in) the fluid. A variety of fluid filter arrangements have been developed for contaminant collection. Improvements are sought.